Do Window Cleaners Have The Dirtiest Windows ?

You often hear builders wives complain their husbands never get around to the house they share with their families.Jobs left for ages while their husbands are off building and renovating other people's houses. Maybe they are being paid at other jobs and they are sick of building and come home for a rest.
I just wondered if window cleaners can be bothered to clean their own windows. Or maybe they employ someone else to clean theirs. Just a silly thought for a wet Saturday.